powerpc/warp: Fix ISA_DMA_THRESHOLD default

If no device is passed to __dma_alloc_coherent, it defaults to using ISA_DMA_THRESHOLD
for the mask. This patch provides a reasonable default rather than 0.

Signed-off-by: Sean MacLennan <smaclennan@pikatech.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
1 file changed